The present invention relates to the field of thread rolling, and more particularly to a thread rolling attachment for an automatic screw machine and to the operation of such attachment.
Present thread rolling attachments generally accommodate a limited range of thread sizes. Where thread rolling attachments are adaptable to a wider selection of thread sizes, they are modified by extensive and complex adjustment cams.
In general, the prior art developments such as in U.S. patents Laemmel No. 2,933,955, Brinkman No. 2,987,945, Hoser No. 3,048,064 and Betker No. 3,314,262 are typical.
The taper adjustment of this attachment is accomplished by a taper adjusting bolt through a split yoke. The fulcrum pins for the thread roll arms are mounted in spherical bearings which allow them to readily align themselves for whatever taper is set.
The primary reason for this is that outboard attachments historically have been prone to disalignment causing tapered threads and all the inherent problems involved.
This taper adjustment allows compensation for the inherent spring in the entire assembly when the rolls are mounted outboard.